Concatenated diverse folded dipoles



United States Patent 3,245,082 CDNCATENATED DIVERSE FOLDED DIPOLES Raymond Alvin Rosenberry, 1501 Superior Bldg., Cleveland, Ohio Filed Sept. 13, 1963, Ser. No. 308,864 12 Claims. (Cl. 343-803) ture for obtaining better performance characteristics and I greater versatility of performance in such antennas.

It is a primary object of my invention to provide an antenna with substantially improved gain characteristics.

It is also an object of my invention to provide such an improved antenna in a compact design which will utilize substantially less physical space than known antenna structures of like performance and will permit utilization of my improved antenna in confined areas or other environments where the reduction in antenna dimension is desirable or important.

Another object of my invention is to provide an antenna having full wave response characteristics in a design which will represent a substantial reduction in bulk and dimension over known full Wave antenna structures.

Still another object of my invention is to provide an antenna of the character described having a differential response characteristic which will achieve broad band performance over a substantial range of frequencies for which it is particularly designed.

A further object of my invention is to provide an antenna of the character described which will have substantially uniform and desirable performance characteristics at the high end, the low end and the averaging point of a band spread or range of frequencies for which the antenna is designed.

Other objects and advantages of my invention will become apparent during the course of the following description.

In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like parts throughout the same,

FIG. 1 is a view in elevation of an antenna structure embodying my invention.

. FIG. 2 is a side elevation of the antenna structure shown in FIG. 1, as viewed from the right hand side of FIG. 1.

FIG. 3 is a plan view of the antenna structure as viewed from the bottom of FIG. 1.

FIG. 4 is a cross-sectional view on an enlarged scale, taken as indicated by the line 44 on FIG. 1.

FIG. 5 is a schematic representation illustrating a modified form of the invention shown in FIG. 1.

Referring more particularly to FIGS. 1-4 of the drawings, I have shown a single element full wave antenna which may also be described as a full wave, phased, folded V antenna, which is fed by current at the low-voltage, lowimpedance points.

Essentially, the antenna consists of. a single continuous electro-conductive element 10, which may be of wire, rod, bar, or any other suitable form of material having known utility in antenna structures. It is recognized that for ice purposes of transportation and shipment, as well as for eas of installation, it may be desirable that the element 10 be supplied in sections which can be coupled and assembled in continuous conductive relationship to provide the single element 10. Therefore, I intend that such an assembled structure shall be embraced by the designation single continuous element as being equivalent to the element 10 illustrated in FIG. 1 of the drawings.

As herein illustrated, the element 10 is a formed aluminum wire which is secured to an insulating mounting plate 11 of any suitable dielectric material.

One end 12 of the element 10v is connected to a feed point or terminal 13 provided on the mounting board, and the opposite end 14 of the element is likewise connected to a feed terminal 15. As is customary, the antenna may be supported in an elevated position by means of a pole, mast or tower, here indicated by the reference numeral 16. As so indicated, the element lies substantially in a vertical plane and can be rotated, if desired, about a vertical axis. However, the antenna is equally effective when disposed in planes other than vertical, such as the plane indicated in FIG. 5, Where the position of the mast 16 is such as to position the antenna in a substantially horizontal plane.

The element 10 extends upwardly and forwardly from the feed terminal 13 as indicated by the portion designated 17. The element is then bent back upon itself, as indi cated at 18, and a portion 19 extends rearward-1y in the same plane as the portion 17, and forming an included angle 20 at the bend 18. The portion 19 terminates in a bend 21 and the element again extends upwardly and forwardly as indicated by the portion 22. For purposes of providing a substantially rigid structure, it may be desirable to provide a point of securement 23 on the mounting plate 11 for clamping or otherwise securing the element to the plate at the point where the bend 21 occurs. The securing means 23 may be in the form of a clamp or screw or other suit-able means. A-n included angle 24 is formed between the portion-s 19 and 22 by reason of the bend 21. The portion 22 terminates in a bend 25 from which the element extends downwardly, as indicated by the portion 26, in a plane slightly behind the plane of the portions 17 and 19, so as to be spaced therefrom. The portion 26 may, for clarity of description, be described as terminating at the midpoint 27 of the antenna. The bend 25 defines an included angle 28 between the portions 22 and 26 of the antenna.

For further convenience in description, the combined portions 17 and 19 of the antenna are designated by the reference character A; and the combined portions 22 and 26 of the antenna are designated by the reference character B.

It will be noted that the lower half of the antenna of FIG. 1 is symmetrical about the midpoint 27 with the upper half of the antenna just described. It includes a comparable portion 29, a bend 30, a portion 31, an included angle 32 between the portions 29 and 31, a bend 34 around securement 23, a portion 33 defining an included angle 35 between the portions 31 and 33, a bend 36, and a portion 37 extending to the midpoint 27 and defining an included angle 38 with the portion 33. The combined portions 29 and 31 are designated by the reference character C; and the combined portions 33 and 37 are designated by the reference character D.

It will be noted that the plate 11 may serve as an insulating and spacing element to prevent electrical contact between the portions 17 and 26 or the portions 29 and 37. It is also desirable that a suitable insulating clamp or spacer 39 be mounted at the intersection of the portions 19 and 26 to prevent contact therebetween at the cross over point, and that similar provision be made at the point where the portion 31 crosses over the portion 37. For clarity of illustration, only one of such insulating clamps 39 has been shown in FIG. 1.

For purposes of example and explanation only, the antenna of FIG. 1 may be considered to-be-designedtfor use on the two meter amateur radio band, which has an established frequency range of 144 to 148 megacycles, the low end of which is favored by amateur operators- A full wave antenna designed for-resonance at'the-low fre quencey end of the band, namely l44 megacycles, would have to be 2.09 metersor-82i3 inches-in length. A full wave antenna in accordance with applicantsdesigrrwould have acomparable end-to-endtsum of 26- and' 37') dimension of about 25% of that length and, additionally, has the differential or broad banding characteristic which is hereinafter described.

In designing such a two meter antennain accordance with the configuration shown in FIG. 1, the single element would be. designed to have a total dimensional length of 82.3 inches, equivalent to the wave length at 144 megacycles. This total physical length of meantenna element. 10 would be divided in selected proportions between the portions A or C and the respective portions B or D. For example, the portion A could'have a length equivalent to 22 /2% of the total wave length; the same would be true of the companion symmetrical portion C, thus accounting for 45% of the total wave length; and the symmetrical sections B and D could each have a length equal to 27 /z% of the total wavelength, thus having a combined lengthmaking up the remaining 55% of the total wave length. These lengths-of the portions A, B, C and D'may in turn be proportioned bet-ween the individual portions in a selected manner. For: example, the portions 17 and 29 would each comprise 10% of the total wave length, equivalent to 16=.5 i'nches-asthe combined length of the two portions; each of the portions 19 and 31 would be 12 /2% of the total wave'lengthand have a combined length of 20.6 inches. The combined length of the portions A and C would be 37.1: inches, equivalent to 45% of the full wave length. at: 144' megacycles; and also equivalent-1 to one-half wave. length at 1.88 meters or 159 megacycles.

The portions 26 and 37 would eachbe'1 3 /z.% of the full wave length for a combined lengthof 22:2- inches; and" the portions-22 and 33 would each represent 14% of the full wavelength or a combined totalz of 23.02 inches as related to the frequency. of 144 megacycles. Thecombined length of the" portions B andv D= would be 45.2 inches, equivalent to 55% of. the full wavelengthat 144 megacycles, and equivalent to.- one-half the wave.- length at 2.29 meters or 131 megacycles.

The antenna portions A and:C incombinatiomwould be dominant and resonant at. 159,: megacycles; the antenna portions B and Din combination would be dominant: and resonant 131 megacycles; the antenna; element; 10; consisting of the sum of the portions A, B, C and D wouldibe dominant and resonant at the: approximate midpoint 015 144 megacycles in the total'designed. band spreadzof: 13-1 159 megacycles for which the antennaisdesigned; The antenv na 16 is thus a. full wave antennahaving an averaging characteristic and a-ditferential: or; broad band featurefor the two meter amateur band, as above described.

By changing the dimension of the portion 17rel'atively to the portion 19 without any change in the total length of the portionA, and makingazlikechangein the portions 29- and 31 of, the portion C, the wave: pattern can; be affected or adjusted without afiecting the over-all: range of the broad banding feature. This islikewisetrueif thedimension relationship between the portions 22 and 26 or 33 and 37 is changed without any change in the total length of the portions B or D.

On the other hand, if the length of the portion A and its companion portion C is decreased and the length of the portions B and D is correspondingly increased so that the total length of the element 10 remains unchanged, the design band spread will be increased, although the averaging characteristic will still be effective at 144 megacycles. Conversely, if the length of the portions A and C is increased relatively to the length of the portions B and D, while retaining the overall length of the element 10 as a constant, the range of the band spread is decreased and the wavepattern is also affected. This type of variation in the design dimensions of the portions of the antenna will have;varying effects upontheresulting wave pattern and can result in an antennain which the portions A and C have a combined length of 55% of the full wave length, and the portionsBand D have a combined length of 45% of the full'wave length, thus providing exactly the same band'spread-as-was described inthe example given above, but-having a completely diiferent wave patternwhich may have undesirable characteristics.

It will also be evident that regardless of the average wave length for which the antenna 10 may be designed, the range of the band spread will alwaysbe a uniform percentage of the average full wave frequency, as long asthe length of the portions A and C are maintained in consistently the same percentage relationship to the portions B and D.

Although I have described the dimensional variations which may be achieved at a particular average frequency design in order to achieve changes in the range of the band spread or in the wave pattern, it must be understood that such dimensional variations can only be accom- 'plished within the limits of retaining the operative configuration of the: antenna. Indiscriminate dimensional variations-may result in a configuration of antenna which will lose its full wave and broad'banding characteristics and will not operate in the manner which I have described; My empirical observations indicate that there is a degree of criticality in the minimum values of the angles 20 and 32 or 28 and 38, below which the antenna assumes a configuration which gives it the characteristics of an ordinary half-wave dipole antenna. It may be broadly statedthat it is desirable that theseangles should be such as will tend to maximize the impedance relationship between the portions of each section A or C and B or D. Thus, taking the section-A as an example, if the angle 20 is made suflicinetly acute, the portions 17 and 19' tend toward close proximity and toward a parallel.-' relationship which would decrease the impedance between these two portions to a point where the symmetrical portions A and C would merely function as a halfwave dipole. The same would be true under similar circumstances of the portions B and D. The minimum value of the angles cannot be stated in absolute terms and, in fact, it is preferable that these angles be as large aspossible. However, other physical and electrical re quirements of the antenna configuration are alsoof importance and must be corelated to achieve a physical embodiment in which each of the critical factors is represented, but comprised or modulated by each of the other factors.

Thus, another of the necessary factors in my antenna is that the portions A and C should be inductively coupled to the portions B and D, respectively, as represented by the portions 26 and 37. On the other hand, it is equally desirable and necessary that the capacitive relationship between these portions be minimized, This is, accomplished by disposing the portions A and, C in close physical, proximity to the portions. 26 and 37, respectively, while at the same time having the portions A and C. crossover the portions 26 and 37- at angles which will minimize the capacitive interrelationship of these portions. These angles are indicated by 40 and 41 for section A and 42 and 43 for section C. Again, it will be apparent that, from the standpoint of minimizing capacitive coupling, it would be desirable that these angles aproach 90". However, it will likewise be apparent that such a configuration would tend to decrease the values of the angles 20 and 32 and thus defeat or nullify the desired maximization of the angles 20 and 32, as previously stated. Furthermore, such an extreme disposition of the portions A and C would not produce a satisfactory wave pattern. Therefore, this is an example of the necessity for compromise in designing my antenna. It-s'hould be noted at this time that the thickness of the mounting plate 11 and the spacing between the portions 19 or 31 and the portions 26 or 37 of the antenna, have been exaggerated in the drawings for purposes of clarity. These portions should be as close to each other as is possible, while still avoiding electrical contact, so that a high degree of inductive coupling exists between these portions to maintain thebroad banding characteristics of the antenna configuration. I

As thus far described, my single element full wave antenna includes the portions A and C, each of which is electrically equivalent to a quarter wave length at the high frequency end of the designed band spread, and in combination equivalent to one-half wave length at that frequency; the portions B and D, each of which is electrically equivalent-to one quarter wave length at the low frequency end of the designed band spread, and in combination being equivalent to a half Wave length at that frequency; and the high frequency portions A and C having an angularly disposed cross-over relationship to the low frequency portions B and D to inductively couple'said antenna portions for resonance at an average frequency intermediate the high end and the low end of the designed band spread. The band spread may be de fined as the difference in value between the resonant frequency of the portion A and the resonant frequency of the portion B. The averaging or mid-range operating frequency can be defined as one-half of the sum of the resonant frequencies of the antenna portions A and B. The portions C and D of the antenna are symmetrical to the portions A and B with reference to the location of the current peak at a half wave length, as indicated by the reference numeral 27, these portions being 180 out of phase electrically to the portions A and B. The feed points 13 and 15 for the antenna are low impedance current feed points which represent current peaks at the other end of the current wave and in'phase with the current peak 27. The bends 21 and 34 represent the high voltage peak points and the high impedance points for the designed half wave length. These high voltage points have a capacitive relationship and should be maintained in close proximity to each other for proper performance of the antenna. However, inductance and/ or capacitance, such as loading coils, may be introduced between the high voltage points to serve as a tuning adiustment for the antenna, if desired, in lieu of or in addition to the tuning adjustment which will now be described.

It will be noted that the mounting plate 11 is provided with a series of apertures or openings 44 to accommodate the feed terminals 13 and 15 at alternative selected positions for tuning purposes. It will be apparent that any change in the position of the feed terminals 13 .and- 15 in one direction or the other, will have some effect on the angularity between the various portions of the antenna; will change the location of the cross over point between the'low and high frequency portions; and will change the distance between the high current feed points and the high voltage points. Empirical tests have indicated that the desired performance of the antenna is glependentupon establishing a matching impedance relationship between the current feed points 13 and '15 and that section of the portions 26 and 37 which is defined between the cross over points of the portions 17 and 29 respectively. It also appears that the configuration of the antenna must be such as to maintain the current feed points 13 and 15, as well as the current peak point 27, sufficiently remote from the high voltage points 21 and 34, so as to maintain a non-matching impedance relationship between the high current points and the high voltage points. Based upon the use of a -75 ohm impedance on the feed, it appears that the foregoing criteria are satisfied when the feed points 13 and 15 are located in an area within the bounds of the low frequency portions B and D, but less than half way toward the high voltage points 21 and 34, as defined by the total distance between the current peak point 27 and the high voltage points. Tuning of the antenna is accomplished by adjustment of the location of the antenna feed points within the defined area, and the openings 44 are provided for that purpose. Therefore, in general, the location of the antenna feed points should be such as to establish the maximum angular differential between the high and low frequency antenna portions, while still maintaining the individual frequency. characteristics of each portion as well as the frequency averaging interrelationship ofthe antenna portions. Under some circumstances, such as for example when a 600 ohm impedance is utilized for the antenna feed, it may become necessary that the feed points be located outside the area which has been previously defined. To provide for the location of the feed points under such circumstances, the apertures 44 in the mounting panel 11 permit the feed points to be located either closer to the high voltage points in one direction, or outside the boundaries of the low frequency portions B and D, in the other direction. The introduction of reactance at the high voltage points, as previously described, or the introduction of reactance in any of the portions, such as 22 and 33, might also create circumstances Which would require the feed points 13 and 15 to be located outside the defined area.

Although, as previously indicated, optimum conformity of the wave pattern is best obtained through use of a balanced low impedance feed on the order of 50-75 ohms, the antenna will give excellent results with a 300 ohm feed, with proper adjustment of the low impedance feed points to match that impedance and a compensating adjustment of the high impedance points 21 and 34. 7

Some of the directional and gain characteristics of my antenna may be of interest. Tests conducted over a period of time showed a 1.4 SWR; a 3 decibel front to back ratio; and a 10 decibel front to end ratio. With the addition of a 5% reflector spaced one-tenth wave length to the back, a front to back ratio of 5:1 was obtained on a reading taken at a distance of 2 wave lengths. It will be understood that my antenna can be used in beams with directors and reflectors, it can be used in stacked arrays, it can be used in multi-stacked arrays, and it can be utilized in combination with elements of similar or dissimilar configuration.

As shown in FIG. 5, the antenna need not be used solely disposed in a vertical plane, but can be mounted for utilization in other planes. Additionally, FIG. 5 schematically indicates a modified form of the low frequency sections B and D which indicates how portions of the element can be bent to achieve desired variations in the wave pattern.

It is of interest that the antenna has directional characteristics, as indicated by the front to back ratio previously mentioned. However, it appears that the front to back ratio exists only at the low and high ends of the designed frequency band spread, and there is no significant front to back ratio or directional characteristic when the antenna is operating at the average frequency. The addition of auxiliary elements, such as directors, will obviously modify this characteristic. If the antenna is operated at frequencies lower than that for which it was designed,

it will lose its directional characteristics, but in contrast to conventional antennas will load, although at a rather poor SW R figure.

On the other hand, the antenna has excellent performance characteristics at the harmonic frequencies, which, coupled with its broad band characteristics, offers a dis? tinct advantage to amateur radio operators who work both the 2 meter and 6 meter amateur bands. A 6 meter antenna designed in accordance with the principles of my invention having a band spread from 4656 megacycles, will work excellently at the third harmonic frequency over a band spread of 138-168 megacycles, thus embracing the l44 l48 megacycle range of the nominal 2 meter amateur band. A conventional antenna structure for 6 meters, has substantially no band spread and just misses the operating portion of the 2 meter band at the third harmonic frequency. It is of interest that, as indicated in the preceding illustration, the band spread does not remain a numerical constant at the harmonic frequencies, although it does represent a uniform percentage variation from the average operating frequency at each of the harmonic frequency resonance levels. It will be recognized that this extension of the broad banding characteristic into the third harmonic frequenly is of particular advantage in antennas for television receiving sets in which the present twelve high frequency receiving channels are divided into two groups, one of which encompasses the third harmonic frequency of the other group.

It will be apparent from the foregoing description that I have provided a full wave differential antenna which retains the bi-directional characteristics of a dipole, but provides full wave transmission or reception in a minimal bulk and space. The antenna has a major dimension which is approximately one-fourth the major dimension of a conventional full wave antenna. Additionally, an antenna designed in accordance with my invention, has the broad banding or band spread characteristic to establish a designed range of frequencies over which the antenna will operate effectively and efficiently. The low and high frequency sections of the antenna also have an averaging function and co-act for resonance at an average mid-point frequency within the designed band spread. The dimensional compactness of the antenna and its consequent reduction in weight, permits my antenna to be used at higher elevations, with less costly supports, and in areas where conventional full wave, or even half wave, antenna structures would be impractical or unsightly.

It will be understood that the forms of my invention, herewith shown and described, are to be taken as preferred examples of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of my invention, or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. In an electro-magnetic wave antenna, the combination of a single conductive element having resonance at a preselected frequency and having an electromagnetic length equivalent to one full wave length at said frequency, a first portion of said element having a configuration and an electromagnetic length having resonance at a frequency lower than said preselected frequency, a second portion of said element having a configuration and an electromagnetic length having resonance at a frequency higher than said pre-selected frequency, and the major axis of said first portion being angularly disposed in inductive relationship to the major axis of said portion to effect a phase shift in the currents in said portions, whereby said first portion and second portion are coupled into mutually interdependent relationship for resonance over a frequency range between said lower frequency and higher frequency.

2. In an electro-magnetic wave antenna, the combination of a first portion having a configuration and an electromagnetic length having resonance at a pre-selected frequency, a second portion having a configuration and an electromagnetic length having resonance at a frequency higher than said pre-selected frequency, means for electrically connecting said first portion and said second portion into a single conductive element having full wave resonance at a frequency intermediate the aforesaid frequencies, and the major axis of said first portion being angularly disposed in inductive relationship to the major axis of said second portion, whereby said first and second portions are coupled into mutually interdependent relationship for resonance over the frequency range between said frequency of said first portion and said frequency of said second portion.

3. In an electromagnetic wave antenna, the combination of a single conductive element having an electromagnetic length of one wavelength at a pre-selectedfrequency, a first portion of said element having an electro magnetic length of one-half wavelength at a second pre-selected frequency lower than said first selected frequency, a second portion of said element having an electromagnetic length of one-half wavelength at a third pre-selected frequency higher than said first selected frequency, and the major axis of saidfirst portion being angularly disposed in inductive relationship to the major axis of said second portion, whereby said portions are coupled for resonance over a frequency range between said second pre-selected frequency and said third preselected frequency.

4. In an electromagnetic wave antenna, the combination of a folded V portion having resonance at a first pre-selected frequency, another portion having resonance at a second pre-selected frequency, a first current wave peak location on said folded V portion, a second current wave peak location on said other portion in phase with said first current wave peak location, a voltage wave peak location on said other portion, means for maintaining said current wave peak locations in non-matching impedance relationship to said voltage peak location, means for connecting said portions into a single conductive element having resonance at an average frequency intermediate said first and second selected frequencies, and the major axis of said folded V portion being angularly disposed in inductive relationship to the major axis of said other portion to effect a phase shift in the currents in said portions, whereby said portions are coupled for resonance over a frequency range between said first and second selected frequencies.

5. A combination as defined in claim 4, wherein said single conductive element has an electromagnetic length equal to a full wavelength at said average frequency.

6. In an electromagnetic wave antenna, the combination of a higher frequency portion having symmetrical configuration about a current wave peak point, a lower frequency portion having symmetrical configuration about a second current wave peak point in phase with said first-named current wave peak point, means for connecting said portions into a single conductive element having full wave resonance at a frequency intermediate the frequencies of said portions, the major axis of said higher frequency portion being angularly disposed in inductive relationship to the major axis of said lower frequency portion to effect a phase shift in the currents in said portions, and means for tuning said coupled portions for resonance over a frequency range between said higher and lower frequencies.

7. A combination as defined in claim 6, wherein each of said higher and lower frequency portions has an electromagnetic length of one-half wavelength at its selected frequency.

8. A combination as defined in claim 6, wherein one of said portions has a high voltage wave peak location defined by intimately-spaced high impedance points thereon, and the other of said portions has its current wave peak point intermediate said high voltage wave peak 9 10 point and the current wave peak point of said one portion. 12. A combination as defined in claim 10, wherein 9. A combination as defined in claim 8, wherein a said one portion is said lower frequency portion. feed line is connected to the current peak point of said other portion to feed both said portions. References cued by the Exammel' 10. A combination as defined in claim 9, wherein said 5 UNITED STATES PATENTS current feed point is adjustably movable relatively to 2 7 1 140 3 195 Ashton said high voltage wave peak point for tuning said an- 2,993,206 7/1961 T 343 ()3 tenna.

11. A combination as defined in claim 10, wherein said HERMAN KARL SAALBACH Exammerone portion is said higher frequency portion. 10 ELI LIEBERMAN, Examiner. 

1. IN AN ELECTRO-MAGNETIC WAVE ANTENNA, THE COMBINATION OF A SINGLE CONDUCTIVE ELEMENT HAVING RESONANCE AT A PRESELECTED FREQUENCY AND HAVING AN ELECTROMAGNETIC LENGTH EQUIVALENT TO ONE FULL WAVE LENGTH AT SAID FREQUENCY, A FIRST PORTION OF SAID ELEMENT HAVING A CONFIGURATION AND AN ELECTROMAGNETIC LENGTH HAVING RESONANCE AT A FREQUENCY LOWER THAN SAID PRESELECTED FREQUENCY, A SECOND PORTION OF SAID ELEMENT HAVING A CONFIGURATION AND AN ELECTROMAGNETIC LENGTH HAVING RESONANCE AT A FREQUENCY HIGHER THAN SAID PRE-SELECTED FREQUENCY, AND THE MAJOR AXIS OF SAID FIRST PORTION BEING ANGULARLY DISPOSED IN INDUCTIVE RELATIONSHIP TO THE MAJOR AXIS OF SAID PORTION TO EFFECT A PHASE SHIFT IN THE CURRENTS IN SAID PORTIONS, WHEREBY SAID FIRST PORTION AND SECOND PORTION ARE COUPLED INTO MUTUALLY INTERDEPENDENT RELATIONSHIP FOR RESONANCE OVER A FREQUENCY RANGE BETWEEN SAID LOWER FREQUENCY AND HIGHER FREQUENCY. 